1. Technical Field of the Invention
The present invention relates to a developer holding member, a development device, a process cartridge and an image forming apparatus, which are used, for example, in a copy machine, a facsimile, a printer or the like. More precisely, the present invention relates to a developer holding member and a development device that form a toner image by conveying a developer held in the developer holding member to a development area where an electrostatic latent image holding member and the developer holding member face each other with a gap therebetween, and then by developing an electrostatic latent image on the electrostatic latent image holding member, and also relates to a process cartridge and an image forming apparatus including the development device. Moreover, the present invention relates to a method of manufacturing a hollow body constituting an external surface of the developer holding member.
2. Description of the Related Art
Various development devices that form images by use of a so-called two-component developer (hereinafter, simply referred to as a developer) containing a toner and magnetic carriers are used in image forming apparatuses such as a copy machine, a facsimile and a printer (see Japanese Patent Application Laid-open Publication No. 2000-347506). Such a type of development device includes a developing roller as a developer holding member that forms toner images by conveying a developer to a development area facing a photosensitive drum as an electrostatic latent image holding member, and then by developing, with the developer, electrostatic latent images formed on the photosensitive drum.
This developing roller includes a developing sleeve and a magnet roller housed in the developing sleeve. The developing sleeve is composed of a non-magnetic material formed in a cylindrical shape. The magnet roller forms a magnetic field for the purpose of causing the developer to form magnetic brushes on a surface of the developing sleeve. When the developer forms the magnetic brushes in the developing roller, the magnetic carriers form chains on the developing sleeve, along lines of magnetic force generated by the magnet roller, and the toner particles adhere to the magnetic carrier chains.
As a method of improving accuracy and durability of a developing roller of this type, Japanese Patent Application Laid-open Publication No. Hei 8-160736 proposes a structure of a developing sleeve including a large number of ridge-like protrusions each having a polygonal shape, and including fine asperities in the portions other than the ridge-like protrusions, and a method of obtaining the asperities by forming a conductive resin coating film, a metallic treatment layer and the like on the developing sleeve.
The structure described in JP-A No. Hei 8-160736, however, has problems that a malfunction such as a decrease in development performance is caused by adhesion of a toner contained in a developer to fine asperity areas when the developing roller is continuously used, and that the manufacturing processing for the developing roller is complicated by its structure.